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[Libvir] Fix handling of config files with duplicate named guests



The code for managing config files in /etc/xen assumed that the filename of
the config matched the name of the guest defined inside. One might thing
this a reasonable assumption, but in the wild I've had reports from users
whom have various config files for the same guest, but with different
settings. This caused some really wierd behaviour in the current code base.
virt-manager display would alternate displaying each config upon refresh!

Now, our API requires that there is only one config per name, so we can't
expose this to the UI. The attached patch, thus simply detects when we 
have more than one config with same named guest, and hides the duplicates.

The way it does this is to change the way we cache configs. Previously we
had a single hash table mapping relative filenames to virConfPtr objects, 
with the implicit assumption that relative filename == guest name. With 
the attached patch we now maintain two hash tables. The first maps fully
qualified pathnames to virConfPtr objects, the second maps guest names
to the first filename found for that name. Thus when querying details for
a guest, we first resolve the guest name to its filename, and then lookup
the virConfPtr object associated with this filename. 

This isn't perfect, but its a hell of alot better than current code, so
I want to commit it as is and figure out more improvement later. There is
no ABI issue here, so we can iterate over impl at will.

Regards,
Dan.
-- 
|=- Red Hat, Engineering, Emerging Technologies, Boston.  +1 978 392 2496 -=|
|=-           Perl modules: http://search.cpan.org/~danberr/              -=|
|=-               Projects: http://freshmeat.net/~danielpb/               -=|
|=-  GnuPG: 7D3B9505   F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505  -=| 
Index: src/xm_internal.c
===================================================================
RCS file: /data/cvs/libvirt/src/xm_internal.c,v
retrieving revision 1.4
diff -u -r1.4 xm_internal.c
--- src/xm_internal.c	14 Dec 2006 01:56:14 -0000	1.4
+++ src/xm_internal.c	19 Dec 2006 18:30:06 -0000
@@ -39,6 +39,7 @@
 
 static char configDir[PATH_MAX];
 static virHashTablePtr configCache = NULL;
+static virHashTablePtr nameConfigMap = NULL;
 static int nconnections = 0;
 static time_t lastRefresh = 0;
 
@@ -132,16 +133,6 @@
 }
 
 
-/* Remove any configs which were not refreshed recently */
-static int xenXMConfigReaper(const void *payload, const char *key ATTRIBUTE_UNUSED, const void *data) {
-    time_t now = *(const time_t *)data;
-    xenXMConfCachePtr entry = (xenXMConfCachePtr)payload;
-
-    if (entry->refreshedAt != now)
-        return (1);
-    return (0);
-}
-
 /* Convenience method to grab a int from the config file object */
 static int xenXMConfigGetInt(virConfPtr conf, const char *name, long *value) {
     virConfValuePtr val;
@@ -217,8 +208,28 @@
 
 /* Ensure that a config object has a valid UUID in it,
    if it doesn't then (re-)generate one */
-static int xenXMConfigEnsureUUID(virConfPtr conf) {
+static int xenXMConfigEnsureIdentity(virConfPtr conf, const char *filename) {
     unsigned char uuid[16];
+    const char *name;
+
+    /* Had better have a name...*/
+    if (xenXMConfigGetString(conf, "name", &name) < 0) {
+        virConfValuePtr value;
+        value = malloc(sizeof(virConfValue));
+        if (!value) {
+            return (-1);
+        }
+
+        /* Set name based on filename */
+        value->type = VIR_CONF_STRING;
+        value->str = strdup(filename);
+        if (!value->str) {
+            free(value);
+            return (-1);
+        }
+        if (virConfSetValue(conf, "name", value) < 0)
+            return (-1);
+    }
 
     /* If there is no uuid...*/
     if (xenXMConfigGetUUID(conf, "uuid", uuid) < 0) {
@@ -262,6 +273,26 @@
 }
 
 
+/* Remove any configs which were not refreshed recently */
+static int xenXMConfigReaper(const void *payload, const char *key ATTRIBUTE_UNUSED, const void *data) {
+    time_t now = *(const time_t *)data;
+    xenXMConfCachePtr entry = (xenXMConfCachePtr)payload;
+
+    if (entry->refreshedAt != now) {
+        const char *olddomname;
+        /* We're going to pure this config file, so check if it
+           is currently mapped as owner of a named domain. */
+        if (xenXMConfigGetString(entry->conf, "name", &olddomname) != -1) {
+            char *nameowner = (char *)virHashLookup(nameConfigMap, olddomname);
+            if (nameowner && !strcmp(nameowner, key)) {
+                virHashRemoveEntry(nameConfigMap, olddomname, NULL);
+            }
+        }
+        return (1);
+    }
+    return (0);
+}
+
 /* This method is called by various methods to scan /etc/xen
    (or whatever directory was set by  LIBVIRT_XM_CONFIG_DIR
    environment variable) and process any domain configs. It
@@ -293,6 +324,7 @@
         struct stat st;
         int newborn = 0;
         char path[PATH_MAX];
+        const char *domname = NULL;
 
         /*
          * Skip a bunch of crufty files that clearly aren't config files
@@ -335,14 +367,24 @@
 
         /* If we already have a matching entry and it is not
            modified, then carry on to next one*/
-        if ((entry = virHashLookup(configCache, ent->d_name))) {
+        if ((entry = virHashLookup(configCache, path))) {
+            const char *olddomname = NULL;
+
             if (entry->refreshedAt >= st.st_mtime) {
                 entry->refreshedAt = now;
                 continue;
             }
-        }
 
-        if (entry) { /* Existing entry which needs refresh */
+            /* If we currently own the name, then release it and
+               re-acquire it later - just in case it was renamed */
+            if (xenXMConfigGetString(entry->conf, "name", &olddomname) != -1) {
+                char *nameowner = (char *)virHashLookup(nameConfigMap, olddomname);
+                if (nameowner && !strcmp(nameowner, path)) {
+                    virHashRemoveEntry(nameConfigMap, olddomname, NULL);
+                }
+            }
+
+            /* Clear existing config entry which needs refresh */
             virConfFree(entry->conf);
             entry->conf = NULL;
         } else { /* Completely new entry */
@@ -355,23 +397,43 @@
         entry->refreshedAt = now;
 
         if (!(entry->conf = virConfReadFile(entry->filename)) ||
-            xenXMConfigEnsureUUID(entry->conf) < 0) {
+            xenXMConfigEnsureIdentity(entry->conf, ent->d_name) < 0) {
             if (!newborn) {
-                virHashRemoveEntry(configCache, ent->d_name, NULL);
+                virHashRemoveEntry(configCache, path, NULL);
             }
             free(entry);
             continue;
         }
 
+        /* Lookup what domain name the conf contains */
+        if (xenXMConfigGetString(entry->conf, "name", &domname) < 0) {
+            if (!newborn) {
+                virHashRemoveEntry(configCache, path, NULL);
+            }
+            free(entry);
+            goto cleanup;
+        }
+
         /* If its a completely new entry, it must be stuck into
            the cache (refresh'd entries are already registered) */
         if (newborn) {
-            if (virHashAddEntry(configCache, ent->d_name, entry) < 0) {
+            if (virHashAddEntry(configCache, entry->filename, entry) < 0) {
                 virConfFree(entry->conf);
                 free(entry);
                 goto cleanup;
             }
         }
+
+        /* See if we need to map this config file in as the primary owner
+         * of the domain in question
+         */
+        if (!virHashLookup(nameConfigMap, domname)) {
+            if (virHashAddEntry(nameConfigMap, domname, entry->filename) < 0) {
+                virHashRemoveEntry(configCache, ent->d_name, NULL);
+                virConfFree(entry->conf);
+                free(entry);
+            }
+        }
     }
 
     /* Reap all entries which were not changed, by comparing
@@ -405,6 +467,12 @@
         configCache = virHashCreate(50);
         if (!configCache)
             return (-1);
+        nameConfigMap = virHashCreate(50);
+        if (!nameConfigMap) {
+            virHashFree(configCache, NULL);
+            configCache = NULL;
+            return (-1);
+        }
     }
     nconnections++;
 
@@ -417,6 +485,8 @@
  */
 int xenXMClose(virConnectPtr conn ATTRIBUTE_UNUSED) {
     if (!nconnections--) {
+        virHashFree(nameConfigMap, NULL);
+        nameConfigMap = NULL;
         virHashFree(configCache, xenXMConfigFree);
         configCache = NULL;
     }
@@ -435,6 +505,7 @@
  * VCPUs and memory. 
  */
 int xenXMDomainGetInfo(virDomainPtr domain, virDomainInfoPtr info) {
+    const char *filename;
     xenXMConfCachePtr entry;
     long vcpus;
     long mem;
@@ -447,7 +518,10 @@
     if (domain->handle != -1)
         return (-1);
 
-    if (!(entry = virHashLookup(configCache, domain->name)))
+    if (!(filename = virHashLookup(nameConfigMap, domain->name)))
+        return (-1);
+
+    if (!(entry = virHashLookup(configCache, filename)))
         return (-1);
 
     memset(info, 0, sizeof(virDomainInfo));
@@ -480,6 +554,7 @@
  */
 char *xenXMDomainDumpXML(virDomainPtr domain, int flags ATTRIBUTE_UNUSED) {
     virBufferPtr buf;
+    const char *filename;
     xenXMConfCachePtr entry;
     char *xml;
     const char *name;
@@ -496,7 +571,11 @@
     }
     if (domain->handle != -1)
         return (NULL);
-    if (!(entry = virHashLookup(configCache, domain->name)))
+
+    if (!(filename = virHashLookup(nameConfigMap, domain->name)))
+        return (NULL);
+
+    if (!(entry = virHashLookup(configCache, filename)))
         return (NULL);
 
     if (xenXMConfigGetString(entry->conf, "name", &name) < 0)
@@ -759,6 +838,7 @@
  * Update amount of memory in the config file
  */
 int xenXMDomainSetMemory(virDomainPtr domain, unsigned long memory) {
+    const char *filename;
     xenXMConfCachePtr entry;
     virConfValuePtr value;
 
@@ -772,7 +852,10 @@
     if (domain->handle != -1)
         return (-1);
 
-    if (!(entry = virHashLookup(configCache, domain->name)))
+    if (!(filename = virHashLookup(nameConfigMap, domain->name)))
+        return (-1);
+
+    if (!(entry = virHashLookup(configCache, filename)))
         return (-1);
 
     if (!(value = malloc(sizeof(virConfValue))))
@@ -797,6 +880,7 @@
  * Update maximum memory limit in config
  */
 int xenXMDomainSetMaxMemory(virDomainPtr domain, unsigned long memory) {
+    const char *filename;
     xenXMConfCachePtr entry;
     virConfValuePtr value;
 
@@ -810,7 +894,10 @@
     if (domain->handle != -1)
         return (-1);
 
-    if (!(entry = virHashLookup(configCache, domain->name)))
+    if (!(filename = virHashLookup(nameConfigMap, domain->name)))
+        return (-1);
+
+    if (!(entry = virHashLookup(configCache, filename)))
         return (-1);
 
     if (!(value = malloc(sizeof(virConfValue))))
@@ -835,6 +922,7 @@
  * Get max memory limit from config
  */
 unsigned long xenXMDomainGetMaxMemory(virDomainPtr domain) {
+    const char *filename;
     xenXMConfCachePtr entry;
     long val;
 
@@ -846,7 +934,10 @@
     if (domain->handle != -1)
         return (-1);
 
-    if (!(entry = virHashLookup(configCache, domain->name)))
+    if (!(filename = virHashLookup(nameConfigMap, domain->name)))
+        return (-1);
+
+    if (!(entry = virHashLookup(configCache, filename)))
         return (-1);
 
     if (xenXMConfigGetInt(entry->conf, "maxmem", &val) < 0 ||
@@ -862,6 +953,7 @@
  * Set the VCPU count in config
  */
 int xenXMDomainSetVcpus(virDomainPtr domain, unsigned int vcpus) {
+    const char *filename;
     xenXMConfCachePtr entry;
     virConfValuePtr value;
 
@@ -875,7 +967,10 @@
     if (domain->handle != -1)
         return (-1);
 
-    if (!(entry = virHashLookup(configCache, domain->name)))
+    if (!(filename = virHashLookup(nameConfigMap, domain->name)))
+        return (-1);
+
+    if (!(entry = virHashLookup(configCache, filename)))
         return (-1);
 
     if (!(value = malloc(sizeof(virConfValue))))
@@ -900,6 +995,7 @@
  * Find an inactive domain based on its name
  */
 virDomainPtr xenXMDomainLookupByName(virConnectPtr conn, const char *domname) {
+    const char *filename;
     xenXMConfCachePtr entry;
     virDomainPtr ret;
     unsigned char uuid[16];
@@ -915,7 +1011,10 @@
     if (xenXMConfigCacheRefresh() < 0)
         return (NULL);
 
-    if (!(entry = virHashLookup(configCache, domname))) {
+    if (!(filename = virHashLookup(nameConfigMap, domname)))
+        return (NULL);
+
+    if (!(entry = virHashLookup(configCache, filename))) {
         return (NULL);
     }
 
@@ -1227,7 +1326,7 @@
     if (!(value = virConfGetValue(conf, "name")) || value->type != VIR_CONF_STRING || value->str == NULL)
         goto error;
 
-    if (virHashLookup(configCache, value->str) != 0)
+    if (virHashLookup(nameConfigMap, value->str))
         goto error;
 
     if ((strlen(configDir) + 1 + strlen(value->str) + 1) > PATH_MAX)
@@ -1253,8 +1352,14 @@
     if (xenXMConfigGetUUID(conf, "uuid", uuid) < 0)
         goto error;
 
-    if (virHashAddEntry(configCache, value->str, entry) < 0)
+    if (virHashAddEntry(configCache, filename, entry) < 0)
+        goto error;
+
+    if (virHashAddEntry(nameConfigMap, value->str, entry->filename) < 0) {
+        virHashRemoveEntry(configCache, filename, NULL);
         goto error;
+    }
+
     entry = NULL;
 
     if (!(ret = virGetDomain(conn, value->str, uuid)))
@@ -1283,6 +1388,7 @@
  * Delete a domain from disk
  */
 int xenXMDomainUndefine(virDomainPtr domain) {
+    const char *filename;
     xenXMConfCachePtr entry;
     if ((domain == NULL) || (domain->conn == NULL) || (domain->name == NULL)) {
         xenXMError((domain ? domain->conn : NULL), VIR_ERR_INVALID_ARG,
@@ -1295,12 +1401,18 @@
     if (domain->conn->flags & VIR_CONNECT_RO)
         return (-1);
 
-    if (!(entry = virHashLookup(configCache, domain->name)))
+    if (!(filename = virHashLookup(nameConfigMap, domain->name)))
+        return (-1);
+
+    if (!(entry = virHashLookup(configCache, filename)))
         return (-1);
 
     if (unlink(entry->filename) < 0)
         return (-1);
 
+    if (virHashRemoveEntry(nameConfigMap, entry->filename, NULL) < 0)
+        return(-1);
+
     if (virHashRemoveEntry(configCache, domain->name, xenXMConfigFree) < 0)
         return (-1);
 
@@ -1354,7 +1466,7 @@
     ctx.max = maxnames;
     ctx.names = names;
 
-    virHashForEach(configCache, xenXMListIterator, &ctx);
+    virHashForEach(nameConfigMap, xenXMListIterator, &ctx);
     return (ctx.count);
 }
 
@@ -1371,7 +1483,7 @@
     if (xenXMConfigCacheRefresh() < 0)
         return (-1);
 
-    return virHashSize(configCache);
+    return virHashSize(nameConfigMap);
 }
 
 /*

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